Accurate calculation of the color that results from overprinting a set of colorants, also called inks herein, is a recognized important problem in the graphic arts.
In the printing industry, there are the standard process inks cyan (C), magenta (M), yellow (Y), and black (K), and red (R), green (G), blue (B) colorants. Today, sometimes more than four inks are used, and the additional inks for printing are typically orange (O), violet (V), and green (G). A spot color is a color made by a single ink, such ink being a pure ink or itself made from mixing a plurality of inks. One example of a spot color is a PANTONE® color. There is a need in the art to accurately predict the spectral characteristics, e.g., the reflectance of an overprint of inks, e.g., process inks and/or spot colors. There is also a need in the art to spectrally characterize spot colors, for example for determining a profile for use in color management, for example to characterize a device that prints using such spot colors on a particular substrate, or for characterizing a device that can reproduce a spot color using an overprint of several colorants on the particular substrate.